Bank 2 cat efficiency on Ford 2.5 V6 / 3.0 V6 Duratec (Mondeo, S-Max, Galaxy ST220) — aging cat and rear O2 sensor drift.
Ford P0430 — Bank 2 cat efficiency on Ford 2.5 V6 / 3.0 V6 Duratec (Mondeo, S-Max, Galaxy ST220) — aging cat and rear O2 sensor drift. Typical UK independent garage cost: £220–£1200.
What actually causes P0430 on a Ford
Ford V6 P0430 is normally just an old cat — these engines run hot and the bank-2 brick (closer to the bulkhead on RHD) ages first. Rear O2 sensor is the cheap test before condemning.
Ford engines that log P0430
- 2.5 V6 Duratec (Mondeo, S-Max)
- 3.0 V6 Duratec ST220
- 2.7 TDV6 (Mondeo)
How we diagnose P0430 on a Ford
- Swap front/rear O2 sensors side-to-side
- Smoke-test upstream
- Borescope cat through rear O2 port
The common misdiagnosis to avoid
Aftermarket cats on ST220 must be Type-Approved for MOT — many performance cats don't pass.
Ford P0430 repair cost in the UK
Expect £220–£1200 including parts and labour at an independent garage. Main-dealer quotes on Ford are usually higher for the same job, and the spread exists because the cheap cause and the expensive cause throw the same code — pay for the diagnosis before you pay for parts.
Bob's workshop tip
ST220 P0430 — fit a quality E-marked aftermarket cat, the OEM unit is silly money.
Codes usually seen alongside P0430 on Ford
- P0420
Symptoms drivers report with P0430
- MIL comes on after a motorway run then stays lit — no drivability change
- Slight sulphur/rotten-egg smell on hard acceleration
- MPG drop of 1–3 mpg you wouldn't notice unless you track it
- Fails emissions/lambda snapshot at MOT despite passing tailpipe CO
- Bank 2 short-term fuel trim slightly richer than bank 1 at cruise
Repairs that clear P0430
- Same diagnostic as P0420 but bank 2 side
- Replace bank 2 rear lambda first as trial
- Confirm with lambda graphing before cat replacement
For the generic, all-makes explanation of this code — meaning, every known cause and UK cost bands — see our P0430 guide.